The present invention is directed to an assembly for use in hydroblast cleaning and, in particular, the hydroblast cleaning of heat exchangers. A typical heat exchanger comprises an outer shell or housing, generally cylindrical, through which a plurality of individual fluid carrying tubes extend. The tubes are typically formed of a heat conductive material such that heat can be exchanged between the fluids flowing through the tubes and fluid flowing about the tubes. During use, heat exchangers become fouled with scale and debris and their efficiency is reduced. Cleaning of such devices typically includes the use of a hydroblasting process in which the interior of the heat exchanger tubes are subjected to a low volume but extremely high velocity water spray. The spray or jets of water generated during hydroblasting may generate several thousand pounds of force. Typically, the hydroblast cleaning of heat exchangers requires the exchanger to be removed from the process area and taken to a cleaning area, usually a large concrete pad where the exchangers are subjected to hydroblast cleaning. The water and debris driven from the heat exchanger are contained on the concrete pad and collected in a sump. The process sprays a considerable amount of water about the surrounding area and generally creates a mess. It would be highly desirable to provide an assembly for use in the hydroblast cleaning of such devices that could better contain the high velocity water and debris extracted therefrom for collection and disposal. It would also be highly desirable if such a system allowed heat exchangers to be cleaned in place. Such a system would not only avoid the mess created with the hydroblast cleaning process but also would result in a substantial savings of time and expense in connection with the cleaning of typical heat exchangers.